Colorado CAFOs linked to ammonia air pollution hotspots

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Levels of airborne ammonia, which can harm people’s ability to breathe, are increasing three times faster each year in Colorado’s Front Range where there are clusters of concentrated animal feeding operations (CAFOs) compared to nearby urban areas without the massive livestock farms, according to a new study. 

The study, published last month in the peer-reviewed journal Atmospheric Environment, adds to mounting evidence that large dairy and livestock farms create hotspots for airborne ammonia, which can irritate people’s eyes and respiratory systems and also react with other airborne pollutants to form particulate matter pollution (PM2.5). PM2.5 particles are tiny air pollutants 30 times smaller than the width of a human hair and inhalation of them has been linked to asthma, heart and lung problems and preterm births. Ammonia contributes to 30% of US PM2.5 pollution, according to estimates. 

The study comes amid lawsuits challenging the state’s monitoring of air and water pollution from CAFOs and, in addition to the human health concerns, highlights the role of agricultural ammonia emissions in the “ecological crisis” in the state’s mountains, including nearby Rocky Mountain National Park, said Jeremy Nichols, a senior advocate at the Center for Biological Diversity. 

The group sued Colorado in April for allegedly failing to hold large slaughterhouses to state air pollution regulations. In a separate lawsuit, the Center for Biological Diversity and Food & Water Watch allege Colorado CAFO permits lack the type of water monitoring needed near lagoons where massive amounts of animal manure and waste are stored. 

“Colorado air regulators are absolutely failing to protect clean air and the environment from these massive animal feeding operations,” said Nichols. “With no reporting, Big Ag gets to remain willfully ignorant while their air pollution smothers the region,” he said. 

“Colorado air regulators are absolutely failing to protect clean air and the environment from these massive animal feeding operations.” – Jeremy Nichols, Center for Biological Diversity 

In the study, Colorado State University researchers measured the airborne ammonia in different areas around northeastern Colorado from 2013 to 2023. They found ammonia concentrations were highest in CAFO-dense regions, and were increasing three times faster in such areas compared to the Denver metropolitan area.

“The largest increases in atmospheric ammonia are closely aligned with the distribution of CAFOs,” the authors wrote. 

Ammonia and CAFOs 

An estimated 80% of atmospheric ammonia, which is a nitrogen-based gas, comes from agriculture via fertilizer and animal manure. In 2023, researchers examined CAFO prevalence and ammonia air pollution across the US and found the levels were highest in counties that had a high density of livestock. The authors wrote “livestock waste is the predominant source of controllable ammonia in the US, a factor of 3 higher than all other sources combined, including fertilizer use.” 

The new research comes as Colorado’s CAFOs expand. The state’s cattle CAFOs now average about 13,000 cows, which is roughly an 80% increase over the past 20 years, according to a Food & Water Watch analysis. The same analysis found the state’s CAFOs generate more than 34 billion pounds of manure each year — more than four times the state’s human waste.

There are other potential causes of ammonia air pollution spikes. The researchers, for example, looked at the impacts from a couple of significant wildfires in the region during the decade of measurements. However, the wildfire smoke would have impacted urban and rural areas in the same way, and not have caused an increase only in certain areas. 

“Wildfire smoke across the region has increased but appears unlikely to explain the majority of the observed atmospheric ammonia increase,” the authors wrote. 

Climate change playing a role

Jeffrey Collett, Jr., lead author and university distinguished professor at Colorado State University’s Atmospheric Science department, said climate change coupled with CAFOs may play an important role in the emissions.

“One hypothesis is that warming temperatures across the region are enhancing ammonia volatilization and emissions from pen surfaces where animal wastes accumulate,” he said. 

In addition to human health concerns, nitrogen deposition in Rocky Mountain National Park — which includes ammonia — continues to harm native species and habitats, prompting state action aimed at reducing such pollutants.  

The Colorado Livestock Association did not return requests for comment on the new study, but has led the industry response on any attempts to regulate CAFOs in the state. Its website says the Association is “front and center” in ongoing discussions about ammonia deposition in Rocky Mountain National Park. 

The association said it “has been engaged in stakeholder meetings and in research on this issue to advocate on behalf of animal agriculture … and working to improve our understanding of the effectiveness of best management practices in lowering ammonia emissions, costs, and challenges to adoption.” 

Leah Schleifer, a spokesperson for the Colorado Department of Public Health and Environment, said the agency hasn’t reviewed the new study but welcomes “research that examines air pollutants.” 

She pointed to the state’s air toxics reporting system that requires some facilities to report ammonia emissions and the Rocky Mountain National Park Subcommittee as ongoing efforts to understand and mitigate ammonia air pollution.

Featured image:  Denver skyline. Credit: Nils Huenerfuerst/Unsplash +